Alingment, lenses and other...

lee · May 4, 2003

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (tschmid @ May 4 2003, 11:48 AM)</td></tr><tr><td id='QUOTE'> </span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (lee @ May 4 2003, 03:39 PM)</td></tr><tr><td id='QUOTE'>It has been well documented that you need to account for the thickness of the paper when focusing on the printing easel.</td></tr></table><span class='postcolor'>
Lee,

I cannot believe this and have not made any such observations. A simple DOF-calculation will show you, that there is plenty of DOF on your easel and EL-Lenses do usually have excellent field flatness. Sometimes when the focus knob on my EL-Head is too far away, I do focus by lowering or lifting the geared easel table on my Durst 139. I'm always surprised about how much I can move the table without losing focus while watching though a 10x grain focuser. </td></tr></table><span class='postcolor'>
what can I say, your experience is different than mine. I use a Peak and I can see the difference even at 8x10. YMMV....

lee\c

Thilo Schmid · May 5, 2003

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (lee @ May 5 2003, 01:59 AM)</td></tr><tr><td id='QUOTE'>what can I say, your experience is different than mine.  I use a Peak and I can see the difference even at 8x10.</td></tr></table><span class='postcolor'>
You mean that if you focus on your easel and then place a piece of paper below your Peak, you will loose focus?
If you state the details (lens, f-stop, and magnificaion), I would like to do a DOF calculation for that.

Have you ever done a double blind test on these results? I often do that when theory dosn't seem to match practice. Most often it turns out as an illusion.

Jorge · May 5, 2003

Thilo, this is a well documented fact or practice. Fred Picker even taped a piece of paper on the bottom of his focus gizmo so he did not have to put it on top of a paper.

My experience is the same, focusing an aerial image with a piece of paper under the peak always yielded sharper prints.

So if you want the info I used a Rodagon G, 2x magnification at f16. Of course with contact printing I dont worry about such pesky details anymore.

Thilo Schmid · May 5, 2003

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Jorge @ May 5 2003, 08:01 AM)</td></tr><tr><td id='QUOTE'>Thilo, this is a well documented fact or practice. Fred Picker even taped a piece of paper on the bottom of his focus gizmo so he did not have to put it on top of a paper. </td></tr></table><span class='postcolor'>
Jorge, it is not the case that I have never heard about that. But I have heard an read about a lot of things that have been handed down without further checking. There are a lot of urban legends around in photography. So please excuse my manner in this case.

BTW: A Rodagon-G is optimized for el-factors above 15x. I dont't think it performs well at 2x. Mine (105 and 150) do not at these scales.

Ed Sukach · May 5, 2003

Is the plane of focus different when the grain focuser is used one-paper-thickness further away? Of course. Is it significant? It depends, but not usually.

I routinely focus with the enlarger lens "wide open" to minimize depth of focus - as much as possible - and stop down for the exposure.

If one is doing the "brick trick", tilting the easel to correct perspective, the effects of depth of focus become apparent. I have differences in paper height, from one side to the other, of as much as an inch and a half - 37 millimeters or so ... and printed "acceptably sharp" at f/16 or f/22, using the 50mm Rodenstock.

What might be interesting is the "Softeners". I purchased two 40.5mm filters from a "bargain box" - out of a curious impulse - only because they *FIT* the Rodenstock enlarging lenses. The only information I have about them is that they are marked "Softener" and they were made in Japan. *Extremely* useful in printing portraits.
Simply wonderful for removing "blemishes" - but *not good* trying to use the grain focuser with them.

Thilo Schmid · May 5, 2003

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Ed Sukach @ May 5 2003, 04:10 PM)</td></tr><tr><td id='QUOTE'>Is the plane of focus different when the grain focuser is used one-paper-thickness further away?  Of course. </td></tr></table><span class='postcolor'>
Ed, if the thickness of a paper sheet would make a significant change to your focus than your enlarger must be adjusted to a fraction of an arc second to be able to provide this plane evenly (otherwise it would depend on where you place your grain focuser). Not to mention an uneven easel or the field curvature of the lens.

Jorge · May 5, 2003

I knew you were going to bring up the el optimization of thr rodagon G, it preformed well enough on a 2x factor. I also have a Schneider Componon S 90 mm for MF enlargements, at f11, and 2.5x factor, I still can see a significant difference between focusing with paper underneath and not.

I assure you this is not one of those urban legends, like " hypo is heavier than water"....

Ed Sukach · May 5, 2003

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (tschmid @ May 5 2003, 06:32 AM)</td></tr><tr><td id='QUOTE'></span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Ed Sukach @ May 5 2003, 04:10 PM)</td></tr><tr><td id='QUOTE'>Is the plane of focus different when the grain focuser is used one-paper-thickness further away?  Of course. </td></tr></table><span class='postcolor'>
Ed, if the thickness of a paper sheet would make a significant change to your focus than your enlarger must be adjusted to a fraction of an arc second to be able to provide this plane evenly (otherwise it would depend on where you place your grain focuser). Not to mention an uneven easel or the field curvature of the lens.</td></tr></table><span class='postcolor'>
I' don't quite understand ....

Have you ever done "The Brick trick"?

P.S. A "fraction of an arc second?" One second would be .000 1 (one ten thousandth) in every 20.0. (take your pick, inches or meters).
I think my Omega is pretty good - but not THAT good.

E.S.

inthedark · May 6, 2003

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (tschmid @ May 4 2003, 11:09 PM)</td></tr><tr><td id='QUOTE'>
BTW: A Rodagon-G is optimized for el-factors above 15x. I dont't think it performs well at 2x. Mine (105 and 150) do not at these scales. </td></tr></table><span class='postcolor'>
Well, now you've confused me, are you saying that the 105 and 150 Rodagons work well at 2.5 or not well. My 150mm is a Schneider Componon-S, it is optimised for 20x, all my other lenses are Rodagon the 105 Rodagon G makes a sweet 30x-35x but is very grainy at 20x or 10x. The 300mm has its sweetest area around a 10x, and the Apo-Ronars from 360mm, 480mm, 485mm, and 760mm, well I don't know their sweet spots. My copy board is on a calibrated track so I am limited in enlargment due to the track length, but they always perform well for the range they are offered.

I didn't understand till recently when I started acquiring lenses, what a difference the right enlarging lens can make!!! Lense are my friends.

Thilo Schmid · May 7, 2003

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Darkroom ChromaCrafts @ May 7 2003, 12:34 AM)</td></tr><tr><td id='QUOTE'>Well, now you've confused me, are you saying that the 105 and 150 Rodagons work well at 2.5 or not well. </td></tr></table><span class='postcolor'>

Jill, the normal Rodagon 105 and 150 do perform well at 2x (although there are better lenses for low magnifications). The Rodagon-G is a special version optimized for mag-ratios >15x (differs depending on focal length). Strictly spoken, each lens has an optimum mag-ratio and is more or less a compromise above and below this point. A normal Rodagon is as bad at 25x as a Rodagon-G is at 2x.

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Darkroom ChromaCrafts @ May 7 2003, 12:34 AM)</td></tr><tr><td id='QUOTE'>My 150mm is a Schneider Componon-S, it is optimised for 20x, all my other lenses are Rodagon the 105 Rodagon G makes a sweet 30x-35x but is very grainy at 20x or 10x.</td></tr></table><span class='postcolor'>

The 150mm Componon-S is not really optimized for 20x, but it may be fine there. Never tried 20x with my Componon-S 150mm. The Schneider counterpart to the Rodagon-G is the G~Componon, which is very rare. I have never seen one. The Componon-S 5.6/150 should be best around 5x-8x.

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Darkroom ChromaCrafts @ May 7 2003, 12:34 AM)</td></tr><tr><td id='QUOTE'>The 300mm has its sweetest area around a 10x, and the Apo-Ronars from 360mm, 480mm, 485mm, and 760mm, well I don't know their sweet spots. My copy board is on a calibrated track so I am limited in enlargment due to the track length, but they always perform well for the range they are offered.</td></tr></table><span class='postcolor'>

I cannot comment on these lenses, but I don't think that the 300mm is best at 10x either. Longer focal lengths are usually optimized to lower mag-ratios. On the other hand they do not fall off that much at higher ratios than shorter focals do.

Aggie · May 7, 2003

Ed Sukach · May 7, 2003

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Aggie @ May 7 2003, 09:36 AM)</td></tr><tr><td id='QUOTE'>whoa,  you mean I have learn about different enlarger lenses now?  Damn I just figured out LF lenses.  So what are the differences for the normal idiot like me who does the home darkroom thing in the future?  I know about 50mm for 35, 75-80 for 645, 100 for 6x7, and 135 for 4x5.  that is the extent of my enlarger knowledge.</td></tr></table><span class='postcolor'>
"Don't be intimidated by the mountains of technical knowledge"
- Stillman Clarke

Yes, each enlarger lens if designed for optimal performance at some specific enlargement ratio. That does *NOT* mean that they are useless at another - only that the designer had that particular charactersitic as a "target", along with many others.

A lens designed for use with 35mm probably would be designed to give the best perfomance at a ratio that would produce an 8" x 10" print. It would be perfectly acceptable at 5" x 7" or 11" x 14" - that "latitude" would ALSO be a design criteria.

There are specialized lenses for the extremes... i.e. enlargements of 6cm x 7cm formats to 30" x 40" inches... and they would be appropriate, and cost justifiable, if one was to often make large prints like that. Otherwise ... the "standard' Rodenstock, Schnieder or Nikon ... or ...? - will be just fine.

aal

Robert · May 7, 2003

Like he said.

A few more things. Some of the 80's will handle 6x7. The 105 are needed for 6x9. 150mm is good for 4x5 to. If you're buying used just get the top of the line lens from any of the big companies. If everything else in your setup is perfect then maybe consider springing for APO lenses.

Avoid the lower priced consumer lenses sold by all the companies. They work but used they aren't much less then the top lenses from the same company.

Some people will tell you to go up a size in lenses. Claiming if you use an 80mm lens for 35mm film it's better. This claim seems to be based on the belief the companies are selling lenses that aren't up to covering the format they are designed for. Going with a longer lens costs you some in terms of enlargement size. A longer lens will need a taller enlarger to get the same max size enlarger.

glbeas · May 7, 2003

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Robert @ May 7 2003, 03:16 PM)</td></tr><tr><td id='QUOTE'> Some people will tell you to go up a size in lenses. Claiming if you use an 80mm lens for 35mm film it's better. This claim seems to be based on the belief the companies are selling lenses that aren't up to covering the format they are designed for. Going with a longer lens costs you some in terms of enlargement size. A longer lens will need a taller enlarger to get the same max size enlarger. </td></tr></table><span class='postcolor'>
I think that is directed more at the condensor or diffuser end of the enlarger. Quite often you will get more even light coverage with the longer focal length lens, which is usually only noticeable when printing expanses of even tones like sky.
The better enlargers mostly can do well enough to not worry about coverage.

Thilo Schmid · May 7, 2003

Aggie,
knowing your enlarger lenses is not less important than knowing your camera lenses. Besides the technical aspects, each lens has its individual characteristics. If I like to have it real sharp and detailed, I mount a 7-element Zeiss on my enlarger. If there is too much sharpness, I'll put on an old uncoated Componon, which still yields better results than a modern lens with a corresponding filter (and sometimes is even cheaper to buy than a good filter). A Zeiss S-Tessar from the 60's (a "low-end" el-lens from Zeiss that still outperforms some modern ones), e.g., passes UV light seamless and can still be focused sufficiently exact with visible light. Or buy a real-low-grade-all-plastic Trinar for 5 bucks (e.g. on Ebay) and try things like coating with wax.

Ed Sukach · May 7, 2003

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (tschmid @ May 7 2003, 12:30 PM)</td></tr><tr><td id='QUOTE'> A Zeiss S-Tessar from the 60's (a "low-end" el-lens from Zeiss that still outperforms some modern ones), e.g., passes UV light seamless and can still be focused sufficiently exact with visible light.</td></tr></table><span class='postcolor'>
Hmm... interesting. What material is used for the elements of this lens?

Thilo Schmid · May 8, 2003

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Ed Sukach @ May 8 2003, 01:14 AM)</td></tr><tr><td id='QUOTE'>Hmm... interesting.  What material is used for the elements of this lens?</td></tr></table><span class='postcolor'>
Ed,
I don't know many specs of that lens. It most probably has normal optical glass. From the name, I would derive that it is a four-element design (which absorbs less UV than a six- or seven element). However, the lens has a strange coating. The MC coatings of Zeiss lenses from a current Apo-Sonnar to 60's Luminar usually have all the same look. This one looks like being neither single nor multi-coated. It has a yellow-brownish reflection.
I have to be more precise about the term "passes UV light seamless". I have not performed any scientific measurements on that and "UV-light" is a flexible term. I have done some experiments with a 390nm bandpass filter and it worked well. The lens might not pass 300nm. I don't know.

Aggie · May 8, 2003

Ed Sukach · May 8, 2003

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (tschmid @ May 8 2003, 12:00 AM)</td></tr><tr><td id='QUOTE'> I have done some experiments with a 390nm bandpass filter and it worked well. </td></tr></table><span class='postcolor'>
Any idea of the amount of attenuation at 390nm?

Donald Miller · May 8, 2003

If this lens does indeed pass 390 nm UV without a large degree of attenuation, then one would be advised to pick them up as an investment. I spoke with Michael Smith the other evening and he has informed me that the developer of the light source for enlarging on Azo has largely finished the development phase. This is a totally new lamp which a manufacturer has developed entirely for this application. So the lens that you have described and it's ability to pass 390 nm UV makes it attractive. What focal lengths was this offered in? I would be looking for a 150 mm if my el nikkor does not provide the necessary band path.

Robert · May 8, 2003

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Aggie @ May 8 2003, 02:11 PM)</td></tr><tr><td id='QUOTE'>
Now how would the enloarging lenses hold up as a lens on a camera? </td></tr></table><span class='postcolor'>
Some people use enlarger lenses for close up work. You need less bellows with something like a 80mm enlarger lens. The bellows factor can slow things down enough that exposure are long enough to not need a shutter. Or I guess in a studio a person could use flash.

Then you have the old way of using your camera lens on your enlarger.

Thilo Schmid · May 8, 2003

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (Ed Sukach @ May 8 2003, 08:54 PM)</td></tr><tr><td id='QUOTE'>Any idea of the amount of attenuation at 390nm?</td></tr></table><span class='postcolor'>
Ed,
I cannot provide absolute values, but this lens was more than 2 f-stops faster on OWRO FB (a discontinued classic silver-rich emulsion FB) at 390nm than a normal 6-element Rodagon. The light source was a normal 300W el-bulb. I have no information on the spectral sensitivity of ORWO FB.

Thilo Schmid · May 8, 2003

</span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>QUOTE (dnmilikan @ May 8 2003, 09:32 PM)</td></tr><tr><td id='QUOTE'>What focal lengths was this offered in? I would be looking for a 150 mm if my el nikkor does not provide the necessary band path.</td></tr></table><span class='postcolor'>
The S-Tessar I am speaking of is a long discontinued lens from the 60's (guessed by its serial no.). I do not know in which focal lengths it had been manufactured. Mine is a 75mm that covers 6x6 and has an excellent overall performance when stopped down to at least f8. It was most likely an OEM-lens for a 60's repro camera.

I would recommend to buy old uncoated or single coated 4-element lenses for that purpose (e.g. Rodenstock Ysaron). They are usually cheap and will transmit UV light better than modern six-element versions. The only problem is, that most of these lenses will suffer from chromatic aberrations and will have a different focus point for visible and UV light. However, most modern lenses (even APO lenses) will have exactly the same problem. On the other hand will shorter wavelengths deliver better resolution. So you may not suffer that much from smaller apertures and extended DOF.

Donald Miller · May 8, 2003

Thanks, I will keep that in mind.

fingel · May 10, 2003

Hey Aggie,
I'll tell you a little bit more about that shutter. It is a LUC shutter, kind of like a packard shutter, but round and uses a standard cable release. It is dial set like the old compur shutters and has 3 settings. Bulb, a shutter speed of about 1/15 sec, and open-for focusing. It fits on the outside of a lens with a diameter of between about 40mm and 52mm by 3 adjustable set screws. I use it on what I think was originally and enlarger lens. It is a 135mm Hermagis Anastigmat Hellor. It is uncoated, has some bubbles in the glass, and has a slight haze. Not what I would want to use for enlarging, but is great for portraits. I haven't shot anything with a modern enlarging lens, but am planning to soon.

Alingment, lenses and other...

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